Ice is heavy and exerts enormous pressure on whatever lies beneath it. Under the ice’s weight, the Earth’s crust bends and as the ice melts the crust bounces up again. Imagine a floating cork, topped with a piece of lead. Will it not pop upwards when the lead is taken off? Similarly, a shrinking ice cap reduces the pressure on the earth’s mantle, causing it to melt and creating magma. Also, this frees tectonic plates up to move against each other and cause the friction needed to initiate earthquakes. This tallies with mathematical models that suggest such processes may potentially lead to more earthquakes, tsunamis and volcanic eruptions.

The cork illustration is way off. Each plate of the earth’s crust covers a significant fraction of the globe, not at all like a bobbing cork. Oceanic crust is 5 to 10 kilometers thick, while glacial ice might be a few hundred meters. And the average density of the crust is 2.7 times the density of ice. The mass of a glacier is not significant relative to the mass of the plate on which it rides.

It is true that ice load can deform the crust, and when that load is removed, the crust will rebound. Most of Michigan, for example, is still rebounding from the retreat of the ice cap (N.B. not a glacier) at the end of the last ice age some 12,000 years ago.

Get that? Still rebounding. So no, the crust doesn’t bob like a cork.

And melting ice doesn’t create magma. I’ll leave that explanation to Steven Goddard at wattsupwiththat.com. Suffice it to say that a reduced overburden of a thick ice layer might effect the melting point of underlying magma by half a degree C or so (out of +/-1,500 deg C). Really insignificant.

A thaw of ice caps caused by global warming may trigger more volcanic eruptions in coming decades by removing a vast weight and freeing magma from deep below ground, research suggests.

“Research suggests“?! What research? Do you have a cite?

Iceland sits astride a mid-ocean ridge, the site of seafloor spreading and the engine that drives North America and Europe two centimeters further apart every year. Iceland is unusual in that it’s above sea level. If you wait around long enough, you’re going to see magma at the surface, glaciers or no.

Back to the original passage: “This tallies with mathematical models…[etc.]”. Again, what mathematical models? Can you produce or cite just one?

All this talk about earthquakes and volcanoes being the result of Global Warming does raise an interesting question. If, as Mr. Matai would have it, warming caused earthquakes and volcanoes at the end of the last ice age some 12,000 years ago, then that rules out volcanic CO2 as a cause of the end of the ice age.

That means increased atmospheric CO2 was a result, not a cause, of warming.